Grinding machine



May 2, 1939.

A. P, BURNS GRINDING MACHINE Filed July 3, 1937 4 Sheets-Sheet lllllllJ. I ll 4 Alfred E Burns w, 2| 7 WW May 2, 1939, A. P. BURNSGRINDING MACHINE 4 Sheet-Sheet 2 Filed July 3, 1937 May 2, 1939. A PBURNS 2,156,9'70

GRINDING MACHINE Filed July 3, l93'7 4 Sheets-Sheet 3 m %W M/ May 2,1939. A. P. BURNS 2,

- GRINDING MACHINE Filed July 3, 1937 4 Sheets-Sheet 4 01: 9 3 fllfmd PBums Patented May. 2, 1939 UNITED STATES PATENT OFFICE The Heald MachineCompany, Worcester,

Mass., a corporation of Massachusetts Application July 3, 1937, SerialNp. 151,885

18 Claims.

The present invention relates to a. grinding machine for the successivereduction of a plurality of workpieces all to a predetermined size, andis particularly applicable to machines for grinding the internalsurfaces of sleeves, bushings and like articles. This application is acontinuationin-part of applicants copending application Serial No.50,777.

In grinding machines of the type disclosed in the Blood Patent No.2,011,705, dated August 20, 1935, the progress of the grinding operationis selectively under the control of the cross-feed mechanism or underthe control of gages which successively enter the bore of the workpieceas the latter approaches and reaches the desired size. When the grindingoperation is under the control of the cross-feed mechanism an axialseparation between the grinding wheel and a workpiece in thework-supporting .tructure is provided prior to completion of thegrinding operation, during which axial separation the grinding wheel isdressed. The dressing tool, which is normally in an inoperativeposition, is moved downwardly, preferably by fluid under pressure, intoalinement with the periphery of the grinding wheel, the movement of thetool occurring during the extended movement of the table which procuresthe relative axial movement between the grinding wheel and workpiece.The crossfeed mechanism is also frequently used for controlling othermachine movements, such as a back-off of the wheel relative to theworkpiece prior to the withdrawal of the wheel from within the workpiececore at the completion of the grinding operation.

In the Blood Patent No. 2,011,705, the crossfeed mechanism is actuatedby a cam which is mounted on the reciprocatory table and is ad justed toengage with a roller forming part of the crossfeed mechanism so that theroller is rocked during each reciprocation of the table. The cam androller arrangement provides for a step-by-step crossfeed movement of thegrinding wheel relative to the workpiece and this step-bystcp advancemay occur at any point of the table travel during the normalreciprocation thereof. Although the cam is preferably adjusted on thetable so that the step-by-step advance of the wheel may occur at one endof the normal reciprocatory movement of the table, but this adjustmentfrequently carelessly made so that the step-by-step advance does notoccur at the desired point. Since the. control mechanism which procuresa runout of the table, either for the dressing operation during thegrinding operation, or for a final separation between the wheel and theworkpiece at the completion of the grinding, is actuated by thecrossfeed mechanism, it would be apparent that the control mechanism isset in operation substantially at the same time that the cam on thetable engages with the roller during one of the table reciprocations.The control mechanism may thus be actuated at any point in the normalreciprocation of the table, dependent upon the position 10 of the tableat the time that the feed cam engages and shifts the roller by which thecrossfeed mechanism is actuated. If the grinding wheel is at the innerend of the workpiece, when the mechanism for shifting the tool is set inop- 15 eration, the downward movement of the dressing tool is controlledby a cam on the machine which is located in a position to engage with aroller carried by the dressing tool support, thereby causing thedressing tool to move smoothly into 20 operative position.

This cam, which controls the dressing tool movement, also cooperateswith the roller in returning the dressing tool support to inoperativeposition when the grinding wheel and work- 2 piece are returned tooperative position, and is thus movable relative to the dressing toolsupport. Thus when the table carries the dressing tool. as in the Bloodpatent aforesaid, the cam is carried by the base of the machine. The camis 3 thus in a position to cooperate with the roller if the dressingtool begins its downward movement while the wheel is still within thebore of the workpiece.

If the grinding wheel is adjacent the outer 35 end of the workpiecewhenthe mechanism for moving the dressing tool is set in operation, theroller on the dressing tool support cannot engage with the cam since thelatter is already longitudinally spaced therefrom. The dressing 49 toolis thus moved rapidly down into operative position, where it is suddenlybrought to rest, with the result that the machine or the tool is jarredand the tool is not properly located. By. the sudden stopping of theswinging tool, the L5 latter does not always remain in its lowermostposition and thus does not produce a smooth periphery on the grindingwheel. This inaccuracy is particularly objectionable when the workpiecesmust be ground to very close tolerances. One of the principal objects ofthe present invention is to avoid the above noted objection by havingthe dressing tool always guided into operative position by the cam whichcooperates with the dressing tool structure and which sub- 55 sequentlymoves the dressing tool upwardly into inoperative position.

Similarly, if the control mechanism by which the back-off is procured isactuated by the crossfeed mechanism, this back-off may occur at anypoint in the normal reciprocation of the table. If the back-off occurswhen the wheel is at the inner end of the workpiece the wheel is backedaway from the work while substantially, the entire length of the wheelis in contact with the workpiece surface and no damage is done to thewheel or work. On the other hand, if the backofi. is initiated at a timewhen the wheel is adjacent to the outer end of the workpiece, the wheelis not always backed away until the axial separation between the wheeland the workpiece has carried the wheel to such a position that only arelatively small portion of the entire length of the wheel is inengagement with the workpiece surface. When this occurs, the workpieceis ground unevenly with the so-called bell mouthing which obviouslyaffects the salability and frequently the utility of the workpiece. Thisbell mouthing results from the increased grinding action of the Wheel onthe workpiece as the length of the line of contact between the wheel andthe workpiece is diminished. One of so that the transverse movement ofthe grinding wheel relative to the workpiece is continuous rather thanby a step-by-step motion, as in the patent above referred to, and thecrossfeed movement is therefore independent of the table reciprocation.In order to avoid the objections above noted in the downward movement ofthe dressing tool into operative position and in the radial back-off ofthe grinding wheel, it is essential that the control mechanism, by whichthe dressing tool is shifted and by which the back-' off is procured, beset in operation when the grinding wheel is at the inner end of theworkpiece. To this end, the present invention involves the provision ofa structure which, in association with the crossfeed mechanism, will setthe control mechanism in operation at the end of the table reciprocationwhen the wheel is at the inner end of the workpiece. By this arrangementthe control mechanism may be actuated by the crossfeed mechanism in thedesired manner, but a suitable interconnection between the controlmechanism and the table reversing mechanism assures that the controlmechanism will function at one end of the table stroke.

According to the present invention the machine is so arranged that themechanism which procures the runout of the table for the dressingoperation is set in motion when the grinding wheel is at the inner endof the workpiece. With the mechanism set in operation at this point, asby mechanism controlled by the table reversing means, the dressing toolis moved downwardly and engages with the cam when the wheel begins its,withdrawal movement relative to the worksupport.

Other and further objects and advantages of the invention will morefully appear from the following detailed description taken in connectionwith the accompanying drawings, in which Fig. 1 is a front elevation ofthe mchine embodying the invention.

Fig. 2 is a front elevation on a larger scale of the mechanism withinthe control box and a portion of the crossfeed mechanism, parts brokenaway to show the construction more fully.

Fig. 3 is an elevation of a portion of the mechanism of Fig. 2 beforethe beginning of thedressln operation.

Fig. 4 is a view corresponding to Fig. 3, showing the position of theparts at the beginning of the dressing operation. a

Fig. 5 is a fluid pressure diagram.

Fig. 6 is a front elevation corresponding to Fig. 2, showing a modifiedtype of grinding machine to which the present invention is applied.

Fig. '7 is a sectional view along the line of Fig. 6.

, Fig. 8 is a sectional view alongthe line 8-8 -of Fig. 7.

Fig. 9 is a fluid pressure diagram for the machine of Fig. 6.

Like reference characters refer to like parts in the different figures.

Referring first to Fig. l, the machine has the usual reciprocatory tableI provided in an internal grinding machine. Either the grinding wheel orthe work to be ground is carried on said table, the reciproacticns ofthe latter operating in either case to procure a relative reciprocatorymovement between said grinding wheel and the workpiece.

In the construction'shown the table supports and carries a workhead 2and a wheelhead 3 is mounted on abridge 4 which spans the guideways, notshown, provided by the base 5 of the machine for the movements of thetable I. The grinding wheel 6 is carried on a spindle 'I journaled inthe wheelhead 3, and the workpiece not shown is mounted in a suitablework-supporting member in the form of a chuck .8 carried on the end of aspindle 9 journaled in the workhead.

Both the grinding wheel and the workpiece are positively rotated as froma driving motor III mounted on the base of the machine. In theconstruction shown, the drive shaft of said motor carries a largediameter pulley ll connected by a belt I2 to a pulley l3 on acountershaft l4 journaled within the base. A second pulley IS on thecountershaft I4- is connected by a belt IE to a small diameter pulley ITon the grinding wheel spindle 1, thereby driving the grinding wheel at ahigh rate of speed. The drive shaft of the motor is also connected to adrum l8 journaled within the base of the machine and connected by a beltH! to a pulley 2|! on the spindle 9. The arrangement of belts andpulleys preferably provides for a rotation of the grinding wheel at amuch higher rate of speed than that of the work-supporting member.

The reciprocations of the table I, which cause the rotating grindingwheel to make the desired traverse over the surface of a workpiecemounted in the chuck, are imparted in any well known manner, as by theuse of the fluid pressure controlling reversing mechanism described inthe Heald 8: Guild Patent No. 1,582,468, dated April 27, 1926. It issuificient to note for the purpose of the present application thatreversal of the table movement at each end of the normal working strokeis procured by the use of spaced reversing dogs 2| and 22 carried byblocks 23 and 24 adjustably secured to the table and adapted a1- e2,188,970 ternately to engage and move a reversing member 26. The latterhas spaced upwardly projecting lugs 26 and 21 which are in a position tobe engaged alternately by the dogs 2| and 22 respectively, while thegrinding wheel is located withinsame shaft 34 to which the reversingmember 25 is secured. Movement of the member 25 accordingly shifts theposition of the valve 28 and reverses the table movement.

Referring now to Fig. 5, fluid under pressure from a pump 35 enters theinlet port 35'.of a casing 36 for the reversing valve 28 throughsuitable throttle and control valve mechanisms hereinafter described.Outlet ports 31 and 38 in the casing 36 are connected by pipes 39 and 49to the left and right hand ends respectively of a cylinder 4| mounted inthe base of the machine. The cylinder has a piston 42 having aprojecting rod 43 which is secured to the table, the reciprocatorymovements of .the piston in the cylinder procuring correspondingmovements of the table.

The relative crossfeed movement between the workpiece ,in the chuck andthe grinding wheel is obtained by movement" of the wheelhead 3transversely on the bridge 4, this movement being procured in anysuitable manner, as by mechanism actuated by the reciprocatory movementsof the table, one form of such mechanism being fully'described in theabove cited Blood et a1. Patent No. 2,011,705. As bestshown in Fig. 2,the wheelhead is mounted on a cross-slide, not shown, movement thereofbeing procured by rotation of a crossfeed screw 44 which engages aninternally threaded portion, not shown, of the cross-slide. Thecrossfeed screw, which is held against longitudinal movement in thebridge, is turned through a ratchet 45 suitably connected to saidcrossfeed screw. Rotation of theratchet is procured by means of a pawl46 which is carried by one arm 41 of a lever 48 journaled on a stud 49on the end of an arm 59 turnable on the crossfeed screw 44. A second arm5| of the lever 48 is engageable with an adjustable stop 52 carried by alug 53 on the arm 59, said stop supporting the lever 48 againstcounterclockwise movement beyond the position shown. The arm 5| alsoengages an abutment 54 in a lever 55 normally held against turningmovement on a stud 56 in the casing 51 which forms a housing for thecrossfeed mechanism. 7

A third arm 58 on the lever 48 is in a position for engagement with aroller 59 on the end of one arm 60 of a bell crank lever 6| pivotallymounted on the stud'56. The other arm 62 of the bell crank lever BI isconnected by a link 63 to the end of one arm 64 of a bell crank lever 65journaled on a stud 66 in the casing 51. The opposite arm 61 of thelever 65 carries a roller 68 which is in a position for engagement witha cam 69 on a block 18 adjustably secured to the table. During eachreciprocation of the table, while the grinding wheel and workpiece arein operative position, the cam engages beneath said roller and procuresan oscillation of the arm 65 and a corresponding upward movement of thepawl 46 for advancing the ratchet 45 clockwise. A step-by-step crossfeedmovement of the grinding-wheel relative to the workpiece is. thus a8sured.

The ratchet wheel 45. and the crossfeed screw I 44 are preferablyconnected by mechanism of the type dlsclosedin the Guild Patent No.1,971,138,

' dated August 21, 1934'. By this mechanism, which forms no essentialfeature of the present invention, the reduction in diameter of thegrinding wheel, as a result of wear and'the dressing operationsperformed thereon, 'is automatically compensated for so that eachsuccessively ground workpiecewill be reduced to the predetermineddiameter independently of variations in the di- For the purpose ameterof the grinding wheel. of the present invention, it will be sufficientto note that a cam 1| is carriedby a ring 12 which is movable relativeto the crossfeed screw and is arranged to be shifted relative thereto,asby the mechanism of the Guild patent, so that when the workpiecereaches a predetermined size said cam will always be at a predeterminedpoint relative to the casing 51. During each grinding operation said camadvances as a unit with the ratchet wheel and crossfeed screw, therelative movement therebetween being procured during the retraction ofthe crossfeed movement between successive grinding operations.

As above stated, the grinding operation is under the control of thecrossfeed movement and to this end the cam 1|, which, during the grinding operation, is advanced clockwise in unison with the ratchet wheel,moves into engagement successively with the ends of adjustable screws 13and 14 carried by an arm 15 of a bell crank lever 16 which is-journaledon the stud 66. The screws 13 and 14 are locked in adjusted positionwithin the arm 15.,' The other arm 11 of the bell crank lever 16 isconnected by a link 18 to an arm 19 secured to a shaft journaled in thecasing 51. A spring 8|, which engages the arm 19,.urges the bell cranklever 16 clockwise into the position of Figs. 2 in readiness for rockingmovement of said lever by the cam 1|.

The shaft 89 projects beyond the casing 51 and'has on the end thereof adepending .arm

82 which carries a bolt 83 by which a horizon-- by a lug 85 on a bracket86 within the control Engagement of the cam 1| with the v box 81. screw13, and subsequently with the screw 14, procures two successivemovements of the horizontal bar 84 .to the left, thereby procuringchanges in the grinding operation through actuation of the controlmechanism, hereinafter described.

'I'he first change in the grinding operation inbell crank lever 88, Fig.2, one arm 89 of which engages a notch 90 in a lug 9| carried by adepending arm 92. The later is journaled on a shaft 93 in the box 81 andis urged counterclockwise-by a spring 94. A bell crank lever 95 alsojournaled on the shaft 93 has a depending arm 96 which engages with apin 91 on the arm 92. The

opposite arm 98 of the lever 95 projects upwardly between the lugs 26and 21 and has a cam surface on its upper end for engagement with thereversing dog 22. Said dog is pivotally connected to the block 24 by apin 24', and the arm 98, when in raised position, elevates the free endof said dog, thereby avoiding engagement between said dog and the lug 21to permit the table to move to the left beyond its normal reciprocatoryposition to carry the grinding wheel past the dressing tool. The arm 98is normally in its lower position shown, with the free end of said armlocated below the dog 22 and out of engagement therewith, being movedupwardly only when the dressing operation is to take place.

As the table moves to the left beyond its normal reciprocatory position,the pivotally mounted carrier 99; having mounted thereon a dressing toolI00, is swung downwardly to move the dressing tool into alinement withthe grinding wheel 6. The dressing tool and the supporting structure areof any suitable construction, as for example, the construction describedin the Blood Patent No. 1,971,848, dated Aug. 28, 1934, in which thedressing tool is moved downwardly into operative position by fluid underpressure. The fluid connection by which the carrier 99 is oscillatedwill be hereinafter described in connection with the re-' maining fluidpressure mechanism. The dressing tool and supporting structure arelocated on the table to provide for a relative movement between the tooland the grinding wheel.

After the dressing tool has passed the grinding wheel during theextended movement of the table to the left, a reversing dog !I pivotallymounted on a pin I02 in a block I03 on the table engages the lug 21 andoscillates the valve 28 to reverse the table movement and restore thegrinding wheel to operative position relative to the workpiece. Duringthe movement of the table to bring the grinding wheel and workpiece intooperative position after the dressing operation, the arm 99 is moveddownwardly into inoperative position by a dog I04 c-ar edby the blockI03 on the table. The dog dEEPicSSGS the arm 98 and rocks the arm 92clockwise, the latter being held against subsequent counterclockwisemovement by a latch I05, the operation of which is fully d scribed inthe aforesaid Blood & Burns Patent through a conduit I0'I, passes arounda reduced Y portion I08 of valve I08 and through a conduit I09 to avalve casing I I0. A valve III in the casing IIO normally provides fluidconnection between the conduit I09 and a second conduit II2 by whichfluid is directed to a throttle valve H3 in a casing H4. The throttlevalve casing H4 is connected by a conduit I I5 to the reversing valve28. Fluid under pressure is thus directed to the reversing valve throughthe throttle valve H3.

The dressing tool is moved downwardly into operative position by apiston IIB slidable in a casing II'I, connected by a conduit IIB to thevalve casing I06. A conduit II9 which provides connection between thecasings I08 and H0 provides fluid connection to the casing Ill. Thevalve III has a full-size portion I20 which normally cuts off the fiowof fluid from the conduit I09 to the conduit I I9. The valve III ishowever, in engagement with the lower end of the arm 92, Fig. 2, andmovement of said arm to the right shifts said valve therewith andestablishes fluid connection between the conduits I09 and H9 to allowfluid under pressure from the pump to pass directly to the casing Illand move the dressing tool into operative position. The connectionbetween the piston I I5 and the dressing tool carrier is by any suitablemechanism, as by the arrangement fully described in the aforesaidBloodPatent No. 1,971,848. The shifting movement of the valve III alsodirects fluid under pressure through a throttled by-pass I2I to the mainthrottle valve H3 for reducing the rate of travel of the table duringthe dressing operation.

The return of the arm 92 substantially to original position after thedressing operation and during the return of the table to normalreciprocatory position restores the valve III substantially to theposition of Fig. 5, thereby cutting ofif the flow of fluid underpressure to the casing III to allow the dressing tool support to bemoved upwardly into the inoperative position of Fig. 1. This returnmovement is posi- 'tively procured by engagement between a cam I22 onthe bridge 4 and a roller I23 on the dressing tool carrier. The cam I22is so located as to move the carrier upwardly as soon 'as the dressingtool passes the wheel during the return movement of the table to normalreciprocatory position. The complete arrangements shown in Fig. 5 arefully described in the aforesaid Blood et al. Patent No. 2,011,705, andnot being essential to the present invention, are not further described.

The above described mechanism is fully disclosed in prior patents orcopending applications and is not of itself a part or the presentinvention. The latter iXlVOl CS he attainment, in connection w th theabove, or similar machine instrumentalities, of the novel andusefulresults herein set forth. According to the present invention themovement of the arm '92 by which the mechanism controlling the dressingoperation is started, occurs only when the grinding wheel is at theinner end of the workpiece. To this end the bell crank lever 33, formingpart of whicluis pivotally mountedxan arm I25, the latter.

being normally urged counterclockwise by a spring I26 positioned betweensaid arm and 2. lug i2? on the lever 33. In the normal position of thearm I25 it is out of engagement with a depending arm I28 of the bellcrank lever 88, as shown 'in Fig. 3, the arm I25 being held against a.pin I29 on the bar 84. The oscillation of the lever 33 thus has noefiect on the lever 88 while the bar 84 remains in the position of Figs.2 and 3. When the screw I3 is elevated by the cam II, however, the bar84 is moved to the left, as above pointed out, moving the pin I29 onsaid bar to the left and thereby swinging the free end of the arm 825 tothe left into the position of Fig. 4. When this occurs, as shown in Fig.4, the, end of the arm I25 engages with the arm I28 and procures aclockwise turning movement of the bell crank lever 98 into the positionshown to release the depending arm 92. g

The bell crank lever 88 is turned by the arm I25 during the clockwiseturning movement of the arm 33 which occurs when the grinding wheelreaches the inner end of the workpiece, at which time the reversing dog2I engages the lug 26 and procures a turning movement of the arm 33. Thecontrol mechanism is thus set in operation when the grinding wheel is atthe inner end of the workpiece and in response to the movement of thetable reversing means. Since the arm 92 moves counterclockwise only whenthe grinding wheel is at the inner end, of the workpi ce. and

40 I33 elevates the arm 98. The free end of thesince the movement or thearm 92 procures a downward movement of the dressing tool into operativeposition, the cam I22 is in a. proper position to engage with theroller-I23 during the downward movement of the tool carrier and causethe dressing tool and its carrier to move downwardly slowly, guided bythe cam I22, until the carrier and tool reach operative position. Duringthe remainder of the grinding operation, after the grinding wheel isdressed, the bell crank lever 88 no longer engages with the notch '90and the contact between the arm I25 and the arm I28 of the bellcranklever has no effect on the grinding operation.

After the grinding wheel and workpiece have been returned to operativeposition, following the dressing operation, the grinding continues withthe grinding wheel given a cross-feed movement until the cam II engagesand elevates the screw I4 to procure a second extended movement of thetable to the left to separate the grinding wheel from the workpiece,thereby bringing the grinding operation to a close. This second extendedmovement ofthe table is procured through a further movement of the bar8-I to the left, swinging the arm I25 even more to the left intoengage.- ment with the depending arm I30, Fig. 4, of a bell crank leverI3I located directly in back of the bell' crank lever 88. This bellcrank lever, as fully described in the above mentioned Blood et al.Patent No. 2,011,705, has an integral latch corresponding to the arm 89of the lever 88 which normally engages in a notch I32 provided by adepending arm I33 corresponding to the arm 92. Said arm I 33 is urgedcounterclockwise by a spring corresponding to the spring 94 and carriesa pin, not shown, which engages with a depending arm, also not shown,integral with the lever 95 so that swinging movement of said arm arm 98is moved higher than it was moved by the previous swinging of the arm 92to elevate the dog It, thereby rendering both the dogs 22 and IIlIinoperative for a movement of the table to the left beyond its normaloperative position,

'ment away from the workpiece surface to prevent engagement between thegrinding wheel and the workpiece during the axial separation thereof.This mechanism may be of any suitable type, as for example, thatdisclosed in Kempton & Galli more No. 1,826,178, dated Oct. 6, 1931, orthe Heald et al. Patent No. 1,816,082, dated July 28, 1931. In thestructure of either of these patents the movement of a plunger by fluidunder pres-' sure procures a temporary radial separation between thegrinding wheel and the workpiece at the beginning of the axialseparation, thereby avoiding the objectionable bell mouthing, otherwiseresulting. Since the lever I3I is rocked by the turning movement of themember 33, which occurs while the grinding wheelisat the inner end oftheworkpiece, this back-off of the grinding wheel will occur before thegrinding.

wheel begins its withdrawal movement from the 15 workpiece bore. I

In the operation of the machine, which will be apparent from theforegoing description, the grinding operation" having been started andthe grinding wheel-being located within the bore of the workpiece, thegrinding operation continues with the wheel reciprocating relative tothe workpiece and with the cam II advanced clockwise for eachreciprocation of the tabe until the screw I3 is engaged and movedupwardly by the cam II for procuring an extended movement of the tablefor the dressing operationjon the grinding wheel. Movement of the screwI3 procures a shifting movement of the bar 84 to the left,

thereby bringing the end of the arm I25 into a position for engagementwith the end of the arm I28. When the reversing members 25 and'33 arenext moved clockwise by the reversing dog 2|, this movement occurringwhen the grinding wheel is at the inner end of the workpiece, thedownward movement of the arm I25 on the member 33 rocks the bell cranklever 88 clockwise and withdraws the arm 89 from the notch 90. Thispermits the arm 92 to move to the right, elevating the dog 22 to permitthe table to move beyond its normal reciprocatory position and, at thesame time shifting the valveI I I to the right to provide fluidconnection from the pump 34 to the cylinder III for procuring a downwardswinging movement of the dressing tool support. Fluid connection to thecylinder I" thus occurs when the grinding, wheel reaches the inner endof the workpiece and,as the dressing tool support swings downwardly, theroller I23 engages with the cam I 22 and the dressing tool isaccordingly moved slowly into operative position, being guided by saidcam. The-dressing tool is carried over the periphery of the grindingwheel and the movement ofthe table is then reversed by the dog II forrestoring the grinding wheel and workpiece to operative position forcompletion of the grinding operation.

After the grinding wheel and workpiece are restored to I operativeposition after the dressing operation, the grinding continues with thegrinding wheel given a further crossfeed movement until the screw Hisengaged and elevated by the cam 'II thereby shifting the bar 84 furtherto the left to bring the end of the arm I25 into alinement with the endof the arm I38 for turning movement of the latter when the'reversingmember 33 is given its next clockwise turning movement. This clockwiseturning movement of the arm 33 occurs when.the table isat'the right handend of its reciprocatory'movement with the grinding wheel at the innerend of the workpiece and this shifting movement of the-member 33 allowsthe depending arm I33 to swing to the right, thereby elevating the arm98 to render the dogs 22 and I0! inoperative for a runout of thetable tothe left to rest position. The swinging movement of the arm I33 alsoshifts'the 'valve I 88 to render the fluid pressure back-off mechanismoperative, thereby avoiding contact between the wheel and the workduring the runout. Theback-ofi is accordingly procured when the grindingwheel is at the inner end of the workpiece by the arm I25 which isrendered operative by mechanism under the control of the crossfeedmovement.

With reference now toFig. 6, the crossfeed mechanism, instead of beingactuated by the table reciprocations as' above stated, is hydraulicallyactuated, as by mechanism of the type shown in the 3100a a Burns PatentNo. 2,027,627. To this 4 end the transverse movement ofthe cross-slideis obtained by rotation of the crossfeedjscrewfl'l (see also Fig. 7)which engages an internally threaded portion, not shown, of thecross-slide, the latter being mounted on a bridge similar to the bridge4 above described, which spans the guideways on which the table isreciprocated.

The crossfeed screw has a gear I38 on the forward end thereof whichmeshes with a pinion I39 secured against turning movement on a shaft I40journalled in a casing MI in which the crossfced mechanism ispositioned, the casing being mounted on the forward end of the bridge.The pinion I39 during the crossfeed movement of the table is rotated inunison with a ratchet wheel I42 which is positively rotated by fluidunder pressure, as hereinafter described. The rotation of the pinion I39procures, through rotation of the crossieed screw, a transverse movementof the grinding wheel relative to the work-supporting structure to causea cutting action onthe workpiece.

As shown in Fig. 7, the shaft I40 has journalled thereon an annularmember I43 having an integral pinion I44, and a vertically extending rodI45, Fig. 6, has rack teeth I46 which are held in engagement with thepinion I44 by a roller I41 journalled on a pin I48 secured in the casingMI. The rod I45 is reciprocated vertically by fluid under pressure forprocuring, during its upward movement, a lateral or crossfeed movementof the wheelhead 3, and during its downwardmovement a retraction of thecrossfeed movement. Again referring to Fig. 7, the sleeve I43 has aflange I49, against which an' annular member I50 is clamped by athreaded nut I5I engaging a porti'on oi the member I43. The member I50thus rotates with the member I43 during a crossfeed movement of thewheelhead or a retraction thereof.

The annular member I50 has spaced studs I52 and I53, Figs.6 and 8,secured by nuts I52 and I53 to said member. Said studs provide pivotalsuports for pawls I54 and I55 normally maintained resiliently inengagement with the ratchet wheel I42 by a spring I56. The pawl I55procures clockwise turning movement of the ratchet wheel in response toa corresponding clockwise rotation of the pinion I44 and the pawl I54procures counterclockwise turning of the ratchet wheel when the pinionI44 is turned counterclockwise.

During the crossfeed movement of the grinding wheel a pin I51 on thepawl I55 is brought into engagement with a shield I58 adjustablypositioned in the casing I. Said shield withdraws the pawl fromengagement with the ratchet wheel I42 without affecting the crossfeedmovement of the wheelhead. During the subsequent retraction of thecrossfeed movement by counterclockwise rotation of the pinion I44 theannular member I55 is allowed to turn counterclockwise relative to theratchet wheel, the pawl I54 being inoperative until the pin I5'I hasbeen moved out of engagement with the shield I58. During the remainderof the retracting movement the ratchet I42 and member I513 rotate inunison and thus procure a retraction of the grinding wheel fromoperative position. The relative movement between the member I5Il andthe ratchet M2 provides for a compensation for the reduction in size ofthe grinding wheel, as will be apparent.

The rod I45, by which the pinion MI is rotated,

is actuated as above stated by fluid under prespiston I60 in a cylinderI5I, the latter being mounted, as shown in Fig. 6, on the base of themachine. Fluid under pressure from a pump I62 is directed through aconduit I63 to a channel I64 in a casing I65 which has a longitudinalbore in which a valve member I66 is slidable, this valve membercorresponding in general to the valve I08 above described. The channelI04 is substantially diametrically opposite to a channel I61 which isconnected by a conduit IIiB'to a port I69 in a casing I10. This casinghas a bore in which a valve I1I, corresponding in general to the valveIII above described is slidable.

A channel I12 in the casing I10 is open at one end to the boreat a pointsubstantialy opposite to the port I69 and at the opposite end opens intothe bore at a point opposite to the port I13. A throttle valve I14 isprovided in the channel I12. The port I13 is connected by a conduit I15to the lower end of the cylinder I5I, an adjustable throttle I16 beingpositioned in the conduit I15, if desired, for controlling the rate ofcrossfeed movement. A port I11 intersects the channel I12 substantiallymidway between the opposite ends of the channel and this port isdirectly opposite port I18 which is connected by a conduit I19 to a portI in a casing I8I.

With the valves I66 and "I in the position shown, these being thepositions of the valves at the beginning of the grinding operation,fluid under pressure is admitted to the conduit I15 from the pump foractuating the crossfeed mechanism, the fluid passing around a reducedportion of the valve I65 and a reduced portion of the valve III. Asecond reduced portion of the valve I'II provides fluid connection betwn the cha nel I12 and the port I13. I

The conduit I15 has a branch conduit I82 communicating with a port I83in a casing I84 having a plunger I85 s lidable therein. A port I86 inthe casing I84 islongitudinally spaced from the port I83 and isconnected by a conduit I81 to a port-I188 in the upper end of thecylinder IIBI, thereby procuring a crossfeed movement of the grindingwheel.

The function and shifting movements of the valves ltd and III, so far asthey control the movements of the table, are fully described in theBlood 8; Burns application Seriai No. 631,334, filed July 20, 1933, nowPatent No. 2,011,705. For the purposes of the present application itwillbe ,sufii-. cient to note that the casing I65, Fig. 9, has a port I92spaced from the port I64 and connected by a conduit its to a port I94 inthe casing I8 I This casing has a longitudinal bore in which the mainthrottle valve I95 is positioned and this valve has a longitudinalrecess I98 which is open at the inner end of the bore in which the valveis located to communicate with a port I91 in the end of the casing. Thisport is connected by a conduit I93 to the inlet port of the casing 36'for the reversing valve 28. The throttle valve has a rectangular notchI95 in line with the port ISI. The throttle valve is also provided witha V-shaped notch 2% adjacent the port I80, thereby providing foradjustment of the flow sol 2,156,970 of fluid from the conduit I19 tothe reversing valve. The throttle valve I95,has a forwardly projectingvalve stem 20I which projects through the cover plate of the control boxon the front of the machine and has a lever, not shown, on the front endthereof, for manual adjustment of the valve. During the operativereciprocation of the table with the grinding wheel reciprocatingrelativeto the surface of the workpiece, fluid is directed through the notch 200by passing around the reduced portion of the valve III which providedfluid connection between the ports I69 and In this modification thegrinding operation is under the control of the crossfeed movement and tothis end the annular member has mounted thereon a cam II which, duringgrinding operation, is advanced clockwise with the member and moves intoengagement successively with the ends of adjustable screws I3 and I4carried by an arm I5 of a bell crank lever 16. which is journalled onthe stud 66. The other arm II of the bell crank lever I6 is connected bya link III to an arm I9 securedto a shaft 80 journalled in the casing51. The shaft 80 has mounted thereon a depending arm 82 which isconnected to a horizontally slidable bar 84. The left hand end of thisbar projects into the control box and is shifted to the left, uponengagement be tween the cam II and either of the screws I3 or 14", foractuating the control mechanism.

The control mechanism of this modification is similar to that abovedescribed. It is sufficient to note for purposes of this modificationthat the lever 88, Fig.6, has one end 89 thereof in a position forengagement with a notch 90 in a lug 9I"carried by a depending arm 92.The latter is journalled on a shaft 93' in the box 81 and is urgedcounterclockwise by a spring 94. A bell crank lever 95, also journalledon a shaft 93, in the box 81 is urged counterclock wise by a spring 94.A bell crank lever 95' also journalled on the shaft 93 .has a dependingarm 96 which engages with a pin 91 on the arm '92.

gage and shift a reversing lever '25 having an integral arm 33. Thereversing leveris. suitably connected to the reversing valve 28' forshifting the latter, thereby directing fluid under pressure to alternateends of the cylinder-4| which is mounted within the base of the machine.A piston 42 within the cylinder has a projecting piston rod 43 suitablyconnected to the table and fluid connection from the reversing valve toopposite ends of the cylinder is providedby conduits'39 and 40'.

In accordance with the present invention the arm 33 has a stud I24 onwhich is pivotally mounted an arm I25, the latter being normally urgedcounterclockwise by a spring I26. In the normal position of the arm I25it is out of engagement with the depending arm I28 of the ent No.2,011,705, above referred to.

is in a position for engagement with the arm I20 when the reversinglever 25' is next shifted clockwise. Clockwise shifting movement occurswhen the table is at the right hand end of its normal reciprocatorymovement at which time the grinding wheel is at the inner end of theworkpiece bore.

When the arm I25 engages the arm I28 the elver '88 is rocked to removethe end 89 from engagement with the notch 90 to allow the depending arm92' to move to the right, thereby elevating the arm 98 to render thereversing dog 22' inoperative and simultaneously to shift the valve IIIto the right for causing a movement of the dressing tool into operativeposition and for discontinuing temporarily the hydraulic crossfeedmovement.

For discontinuing the crossfeed movement during the dressing operation,the valve III has a full-sized portion, which, when the valve is shiftedto the right, closes the port I13, thereby preventing the entry of fluidunder pressure to the cylinder I BI below the piston I60 while the valveIII is in its right hand position. When the valve III is restored to itsoriginal position, during the return of the grinding wheel and workpieceto operative relation, fluid connection is again established through theport I'I3 to the cylinder ISI for procuring a further crossfeedmovement.

The dressing tool is moved downwardly into operative position by apiston H6 slidable in a casing II'I connected by a conduit II8 to a portin the valve casing I65 and a similar port directly opposite isconnected by a conduit II9 ,to the valve casing I10. The valve III has afull sized portion which normally cuts off the flow of fluid from theconduit I 68 to. the conduit 9', but

whn the valve III is shifted to the right, fluid connection betweenthese two conduits is established to allow fluid under pressure to enterthe casing III for movingthe dressing tool into operative position. Theconnection'between the piston H5 and the dressing tool carrier may be,for example, that shown in the above mentioned Blood Patent No.1,971,848. The shifting of the valve III also directs fluid underpressure through the throttled channel I12 for reducing the rate oftravel of the table during the dressing operation.

After the dressing tool has been carried past the grinding wheel duringthe extended movement of the table to the left, the reversing dog I Icarried by the block I03 on the'table engages and shifts the reversinglever 25 for reversing the table movement. During the subsequentmovement of the table to the right to restore the grinding wheel andworkpiece to operative relation, the arm 98' is moved downwardly intoinoperative position by a pivotally mounted dog I04 carried by the blockI03. Downward movement=of the arm 98 involves a corresponding movementof the arm 92 to the left substantially to its original position, whereit is held by a latch I fully described in the Blood 8: Burns Pat- Thereturn of the arm 92 to its original position following the dressingoperation returns the valve I'II substantially to the position ofFig'.9,

workpiece have been returned to operative relation following thedressing operation the grinding action continues extended movement ofthe table for axially separating the grinding wheel and workpiece. Thissecond extended movement of the table results from a further movement ofthe bar 84' to the left, thereby moving the arm I25 into a position forengagement with the depending arm I36 of a bell crank lever I3I' located*directly in back of the bell crank lever 88'. This bell crank lever, asabove described, has an integral latch corresponding to the arm 89 ofthe lever 88 which normally engages in a notch I32 provided by adepending arm I33 corresponding to the arm 92'. The arm I33 is urgedcounterclockwise by a spring corresponding to the spring 94' and uponswinging movement to the right procures a corresponding upward movementof the arm 98, this elevating movement being higher than during theprevious upward movement of 'the lever, thereby rendering both dogs 22'and IOI' inoperative to allow the table to move to its extreme righthand position, where it isv brought to rest.

" The lower end of the arm I33 engages with the valve. I66 to shift saidvalve to the right,

thereby establishing fluid connection from the pump through the conduitI89 to the upper end of the cylinder I6I for a retraction of thecrossfeed movement. When fluid enters the upper end ofthe cylinder H6,fluid under pressure is also directed to the upper end of the casing I84to shift the plunger I85 downwardly, establishing fluid connectionbetween the port I83 and an exhaust port 202 for the exhaust of fluidunder pressure from the underside of the piston I66. Fluid connectionfrom thepump to the conduit I89 is provided by a channel 203 provided inthe valve I66.

Although the operation of the modified machine disclosed in Figs. 6 to 9inclusive, will be apparent from the foregoing description, it will bebrieflysummarized. After the grinding operation has'been started withthe grinding wheel positioned 'in the bore of the workpiece, thegrinding continues in the usual manner until the cam II has engaged and.elevated the screw I3, thereby shifting the bar 84' to the left,.Fig. 6,carrying therewith the lower end of the arm I25. During the subsequentclockwise movement of the reversing lever 25' when the table is at theright hand end of its movement, the arm I25 rocks the lever 88, therebyprocuring an extended movement of the table to the left by renderinginoperative the reversing dog 22. The valve III is simultaneouslyshifted to the right, procuring movement of the dressing tool intooperative position, andv also temporarily interrupting the hydraulicallyactuated crossieed movement.

After the dressing tool has been carried past the grinding wheel thereversing dog iti shifts the reversing lever and causes the table tore-,

turn to operative position, the arm 88' and-the valve I'II beingrestored to original position during the return movement of the table.The rea turn of the valve III allows the dressing tool to be returned toinoperative position and again sets the crossfeed mechanism inoperation.

Grinding continues subsequent to the dressing operation until the cam IIelevates the screw I4, thereby shifting the arm I26 still further to vthe left into a position for engagement with the the workpiece.

aioaovo of the table travel. The arm I30, is a part of the lever MI andmovement of this lever releases the depending arm I33 for againelevating the arm 98 and for shifting the valve I66 to the right.Elevation of the arm 98 causes the table to move to the left toinoperative position and movement of the valve I66 procures a retractionof the crossfeed movement.

From the foregoing it will be apparent that the present inventionprovides for setting in operation the mechanism which procures themovement of the dressing tool into operativeposition only when thegrinding wheel is at the inner end of the workpiece, so that thedressing tool during its movement into operative position will be guidedby the same cam whichsubsequently returns the dressing tool toinoperative position. The mechanism which actuates the dressing tool isset in operation by the reversing member through which the tablemovements are procured,

and is actuated when the reversing member is shifted at one .end of thetable movements The same mechanism which procures the movement of thedressing tool at the desired point, also may be used for setting othermechanism in operation when the grinding wheel is at the inner end ofSuch other mechanism may be the structure by which the back-off oi thegrinding wheel is obtained. Where the crossfeed movement is independentof the reciprocations of the table the present invention provides forcausing the changes in the grinding operation to take place at one endof the normal reciprocation of the table rather than independentlythereof, as would occur if the changes in the grinding operation wereunder the control of the crossfeed mechanism without any interconnectionbetween the control mechanism and the reversing means for the tablemovement.

I claim:

1. In a grinding-machine, a grinding member, a work supporting member, areciprocatory table on which one or said members is mounted forprocuring a relative movement therebetween, reversing means for saidtable, control means for procuring a change in the grinding operation,actuating means for said control means auto- 'matically operative at apredetermined point in tween said actuating means and said reversingmeans for procuring actuation of said control means by said actuatingmeans only at one end of the table movement.

2. In a grinding machine, a grinding member, a work-supporting member, areciprocatory table on which one of said members is mounted forprocuring a relative movement therebetween, reversing means for saidtable, controlmeans for procuring a change in the grinding operation,actuating means for said control means automatically operative at apredetermined point in the grinding operation and independently of theposition or the table, and means associated with the reversing means andproviding a connection between said actuating means and said controlmeans for actuating said control means only in response to movement ofsaid reversing means.

3. In a grinding machine, a grinding member, a work-supporting member, areciprocatory table on which one of said members is mounted forpromovement and actuated by movement of said re-' curing a change in thegrinding operation, actuating means associated with said reversingmeansfor rendering said control means operative in response to shifting ofsaid reversing means, means for procuring a crossfeed movement betweensaid members, and means under the control of the crossfeed movement forshifting said actuating means into operative position.

4. In a grinding machine, a grinding member, a work-supporting member, areciprocatory table on which one of said members is mounted forprocuring a relative movement therebetween, re-

versing means for said table, control means for procuring a change inthe grinding operation, actuating means associated with said reversingmeans for rendering said control means operative in response to shiftingof said reversing means, means independent of the table reciprocationsfor procuring a crossfeed movement between said members, and means underthe control of the crossfeed movement for shifting said actuating meansinto operative position.

5. In a grinding machine, a grinding member, a work-supporting member, areciprocatory table on which one of said members is mounted forprocuring a relative movement therebetween, re-

versing means for said table, control means forprocuring a change in thegrinding operation, means for procuring a crossfeed movement betweensaid members, means responsive to said crossfeed movement for actuatingsaidcontrol means, and means associated with the reversing .means andproviding a connection between said actuating means and said controlmeans whereby 'said actuating means procures actuation of said controlmeans only in response to movement of said reversing means.

6. In a grinding machine, a grinding member, a work-supporting member, areciprocatory table on which one of said members is mounted forprocuring a relative movement therebetween, reversing means for saidtable, control meansfor procuring a change in the grinding operation,means independent of the table reciprocations for procuring a crossfeedmovement between said -members, means responsive to said crossfeedmovement for actuating said control means, and means associated with thereversing means and providing a connection between said actuating meansand said control means whereby said ac- ,tuatingmeans procures actuationof said control means only in response to movement of said awork-supporting member, a reciprocatory table on which one of saidmembers is mounted for procuring a relative movement therebetween, re-

versing means for said table, control means for procuring a change inthe grinding operation, a latch for holding said control means ininoperativeposition, means for procuring a crossfeed movement betweensaid members, and means rendered operative in response to said crossfeedversing means at one end of the table movement for tripping said latchl-9. Ina grinding machine, a grinding member,

. a work-supporting member, a reciprocatory table on which one of saidmembers is mounted for procuring a relative movement therebetween,reversing means for said table, control means for procuring a change inthe grinding operation, a latch for holding said control means ininoperative position, actuating means for said latch carried by saidreversing means, and means automatically operative duringthe grindingope'ration -for shifting the actuating means into latch engagingposition.

10. In a grinding'machine, a grinding member, a work-supporting member,a reciprocatory table on which one of said members is mounted forprocuring a relative movement therebetween, reversing means for saidtable, control means for procuring a change in the grinding operation,a'latch for holding said control means in inoperative position,actuating means for said latch carried by said reversing means, meansfor procuring a crossfeed movement between said members, and meansresponsive to said crossfeed movement for shifting the actuating meansinto latch engaging position. v

11. In a grinding machin ,a grinding member, a work-supporting member, areciprocatory table for one of said members for procuring a relativemovement therebetween, a dressing member mounted for movement relativeto the grinding member in response to the table mover ment, saiddressing member having an inoperative and an operative position inalinement with the position of the grinding member, reversing means forsaid table, control means for procuring movement of the dressing memberinto op- I erative position, means for procuring a crossfeed movementbetween the grinding member and the work-supporting member, means onsaid reversing means for rendering said control meansoperative',,and-means responsive to the crossfeed movement for shiftingsaid last means into operative position;

12. In a grinding machine, a grinding member, a dressing member havingan inoperative and operative position in alinement with the periphery ofthe grinding member, a reciprocatory table for one of said members forprocuring a relative movement therebetween, reversing means for saidtable, control means for procuring movement of the dressing member intooperative position, a cam in fixed relation to the grinding ,member formoving the dressing member out of operative position, and means on thereversing means for rendering said control means operative to procuremovement of the dressing memberinto operative position at one end of thetable movement, whereby said cam will guide the dressing member intooperative position.

13. In a grinding machine, a grindin .mem-

her, a work-supporting member, a table on which one oii said members ismounted and whose movement procures a relative axial movement betweensaid members, reversing means for reversing the direction of movement ofthe table, automatic control means for interrupting the normalreciprocatory movements of said table, a latch for normally retainingsaid control means in an inoperative position, meansfor procuring acrossfeed movement between said members, means on, said reversing meansfor actuating said latch, and mechanical elements adaptedto be shiftedin response to the crossfeed movement for rendering said lastmeansoperative.

14. In a'grinding machine, a grinding member, a dressing tool memberhaving an inoperative and an operative'position, a table on which ingsaid other means operative.

15. In a grinding machine, the combination with a grinding wheel, adressing tool having an operative and an inoperative position, a tablefor procuring a relative movement between said parts, means including areversing member and reversing dogs for reversing the direction ofmovement oi. said table, cam means for moving the dressing tool out oioperativeposition, actuating means for shifting the tool into operativeposition, and control means for said actuating means, of meansassociated with said control means and forming a part of the reversingmeans to provide for actuation of said control means only atone end ofthe table movement, said cam being positioned to guide the tool intooperative position.

16. In a grinding machine, the combinationwith a grinding member, awork-supporting member, a table on which one of said members is mountedfor procuring a relative ,movement therebetween, a dressing tool havingan operative and an inoperative position and mounted for movementrelative to the grinding member in response to the table movement, meansincluding a reversing member for reversing the direction of movement ofsaid table, cam meansi'or moving the dressing tool out of operativeposition, actuating means for shifting the tool into operative position,and control means for said actuating means, of means associated withsaid control meansand forming a part of the reversing means toprovidefor actuation of said control means only at one end of the. tablemovement, and means automatically operative during the grindingoperation for rendering said last means operative.

17. In a grinding machine, the combination with a grinding member, awork-supporting member, a table on which one of said members is mountedfor procuring a relative movement therebetween, a dressing tool havingan opera tive and an inoperative position and mounted for a part of thereversing means to provide for 'actuation of said control means only atone end of the table movement, and means responsive to the crossfeedmovement to render said last means operative. I

18. In a grinding machine, a grinding member, a work-supporting member,a reciprocating table on which one of said members'is mounted forprocuring a relative movement between said members,reversing means forthe table, control means for procuring a radial separation between saidmembers and simultaneously an axial separation therebetween by anextended movement of the table,-actuating means associated with saidreversing means for rendering said control means operative in responseto shifting of said reversing means, means for procuring a crossi'eedmovement between said members, and means responsive to said crossfeedmovement for shifting said actuating means into operative position.

ALFRED P. BURNS.

